CALDWELL -- A five-vehicle crash sent multiple people to the hospital and blocked westbound I-84 for hours overnight.

The crash happened at 11:13 p.m. Monday at milepost 30.

According to Idaho State Police, the chain reaction of collisions happened after a 1996 International truck stopped in the westbound lanes facing south.

Four cars and a semi truck, all headed westbound, struck the International truck or each other. Two of the car drivers, 19-year-old Austin Vassar of Nampa and 61-year-old Catherine Vandiver of Nampa, were injured in the wreck, and were taken by ambulance to Saint Alphonsus Regional Medical Center in Boise.

The crash blocked the westbound lanes for about four hours.

It's unclear why the International truck was stopped on the interstate. The wreck remains under investigation.